The present invention relates to a vibratory parts-feeding unit and, in particular, to a parts-feeding unit having a pair of linear-transferring means for transferring, by vibration, parts in mutually opposite directions.
In general, as a vibratory parts-feeding unit, which transfers and feeds minute parts by vibration, a parts-feeding unit, which is constructed by connecting a vibratory linear-feeder is connected to the exit of a vibratory parts-feeder having a bowl-shaped vibrating tray, is known. In this parts-feeding unit having a bowl-shaped vibratory parts-feeder, a spiral parts-feeding path is formed inside the vibrating tray, and at a part of this parts-feeding path, a parts-screening portion for making the posture of parts uniform or screening the parts quality is provided.
However, in this parts-feeding unit having a bowl-shaped parts-feeder, since it is necessary to provide a parts-screening portion on a spiral parts-feeding path, the vibrating tray itself having the spiral parts-feeding path becomes expensive, moreover, respective components of the parts-screening portion, which is fabricated in response to this parts-feeding path, also become expensive. Therefore, a problem exists such that a reduction in manufacturing cost is difficult. In addition, if an improvement in parts-feeding ability is intended in this unit, it is necessary to enlarge the diameter of the vibrating tray. Furthermore, in this unit, in order to transfer and mount aligned parts from the bowl-shaped parts feeder to the linear feeder, the linear-feeder which linearly vibrates must be connected and arranged in a condition where a minute distance is provided with respect to the vibrating tray which vibrates in the tangential direction (in a twisted motion). However, since high accuracy is required for this connection area, assembly and maintenance are difficult, and a problem also exists such that parts-feeding path is easily clogged with parts at the connection area.
Therefore, in place of such a former expensive parts-feeding unit having a bowl-shaped parts feeder whose installation area is great considering its parts-feeding ability as described above, in recent years, a successor circulating parts-feeding unit, which is low cost and downsizable, has received considerable attention. This circulating parts-feeding unit is of a construction such that a pair of vibratory linear feeders which transfer parts in the mutually opposite directions is closely juxtaposed, parts are fed by one of the linear feeders (feeding linear feeder), and parts rejected from a parts-screening portion in a feeding process of these parts are received by the other linear feeder (collecting linear feeder) and transferred in the opposite direction so as to return the upstream side of the feeding linear feeder. In further detail, a construction is provided, wherein a parts-screening portion is provided at a position on the downstream side of a parts-feeding path of the feeding linear feeder so that parts rejected from the parts-feeding path in a process for aligning parts are guided to a position on the upstream side of a parts-collecting path of the collecting linear feeder, and a construction is provided, wherein a parts feedback portion is provided at a position on the downstream side of the parts-collecting path of the collecting linear feeder so that parts are returned from this parts returning portion to a position on the upstream side of the parts-feeding path of the feeding linear feeder. This type of unit is disclosed in the Japanese Patent Opening Gazette No. 1998-175724, No. 2001-63816 (this is corresponding to U.S. Pat. No. 6,374,985), and Japanese Patent No. 1988-53084.
However, in the above circulating parts-feeding unit, if a pair of linear-feeders having mutually opposite transferring directions is juxtaposed, it is necessary to construct both linear feeders so as not make contact with each other and, in order to enable parts delivery (transfer) between the pair of linear feeders, it is also necessary to provide a construction with a crossing arrangement such that the upstream side of the parts-collecting path of the collecting linear-feeder is arranged slightly downward the downstream side of the parts-feeding path on the feeding linear feeder and the downstream side of the parts-collecting path is arranged slightly above the upstream side of the parts-feeding path. Accordingly, with respect to the whole length of the pair of linear feeders, the length of a range of the parts-screening portion, that is, a range where parts can be rejected from the feeding linear feeder to the collecting linear feeder is limited, therefore, a problem exists such that downsizing of the unit and performance (parts screening ability) of the unit are hardly compatible, for example, in some cases, parts-feeding ability declines and inferior parts-screening increases.
In addition, as in the above, since the pair of linear feeders mutually cross when viewed in the up-and-down direction, portions of the feeding linear-feeder and collecting linear feeder; which are mutually opposed with a slight distance in the horizontal direction, inevitably exist at a cross point. Therefore, maintainability is poor and a problem also exists such that parts and/or dust drops and clogging in the gap between such opposed portions, causing a motion failure of vibrating movement in both of linear feeders.
Furthermore, as described in the above, in the pair of linear feeders of a crossing arrangement, when one of the parts-feeding path of the feeding linear-feeder or the parts-collecting path of the collecting linear-feeder is constructed to become horizontal, the other is accordingly arranged with an inclination so as to become an upslope toward a parts transferring direction. Therefore, problems also exist such that a feeding rate at the parts-feeding path declines or the flow ability of parts on the parts-collecting path becomes low.
Therefore, the present invention is made to solve the above problems, and it is an object thereof to provide a vibratory parts-feeding unit wherein downsizing and an improvement in performance of the unit can be compatible. In addition, it is an object to provide a parts-feeding unit wherein an improvement in maintainability and a reduction in motion failure is possible. Furthermore, it is an object to provide a parts-feeding unit wherein an improvement in parts feeding ability is possible.
In order to achieve the above objects, a vibratory parts-feeding unit of the present invention comprises:
(a) first linear-transferring means for screening and feeding parts while transferring the parts along a parts-feeding path by vibration,
(b) parts-lifting means for raising parts from a parts-receiving portion located downward and feeding the parts to the upstream side of said first linear-transferring means by a parts-sending portion located upward, and
(c) second linear-transferring means which has a parts-collecting path, receives parts rejected from said parts-feeding path, and transfers the parts in a direction opposite to that of said first linear-transferring means along said parts-collecting path by vibration to return the parts to said parts-receiving portion of said parts-lifting means.
According to this invention, in the process where parts are fed along the parts-feeding path of the first linear-transferring means, parts rejected from the parts-feeding path through parts-screening are transferred and mounted onto the parts-collecting path of the second linear-transferring means, transferred along the parts-collecting path in the direction opposite to a parts feeding direction, and returned to the parts-receiving portion of the parts-lifting means. Therefore, the parts are furthermore lifted upward by the parts-lifting means and fed from the parts-sending portion to the first linear-transferring means. Accordingly, in the feeding process of parts, some of the parts circulate through the first linear-transferring means, the second linear-transferring means and the parts-lifting means. Namely, in the present invention, parts collected on the parts-collecting path of the second linear-transferring means pass over, by being lifted by the parts-lifting means, a connecting step to the parts-feeding path of the first linear-transferring means and are introduced into the first linear-transferring means.
With such a construction as in the above, parts are to be lifted by the parts-lifting means, whereby making it unnecessary to incline the parts-collecting path of the second linear-transferring means with respect to the parts-feeding path of the first linear-transferring means, therefore, it becomes possible to reject parts from any place on the parts-feeding path of the first linear-transferring means, and it becomes possible to form a long parts-screening portion. Consequently, it becomes possible to heighten the parts feeding rate without decreasing screening ability (screening rate and screening accuracy). In addition, the length of the parts-screening portion can be sufficiently secured, whereby making it possible to shorten the overall length of the first linear-transferring means, thus, the unit can be downsized. Furthermore, since it is unnecessary to incline the parts-collecting path with respect to the parts-feeding path, it becomes possible to, for example, arrange the parts-collecting path below the parts-feeding path, whereby the distance between the first linear-transferring means and second linear-transferring means can be sufficiently secured while providing a construction so that parts can be transferred between the parts-feeding path and the parts-collecting path, whereby maintainability in gap adjustment, etc., can be improved, and also problems such that parts and/or dust intruding in the gap between both in different vibrating modes, causing a motion failure can be prevented.
In particular, as a first invention, since the parts-collecting path of the second linear-transferring means is arranged, as a two-dimensional view (a plan view), approximately in parallel with respect to the parts-feeding path, it becomes possible to arbitrarily set the range for delivering parts between the parts-feeding path and parts-collecting path. Therefore, it becomes possible to freely design the length of the parts-screening portion on the parts-feeding path. In greater detail, by appropriately designing and replacing a vibrating body having the parts-feeding path of the first linear-transferring means or a detachable unit for parts-screening constructed as one portion of this vibrating body, unit construction can be simply altered according to the properties of parts to be fed and the feeding mode of parts without modifying the basic unit construction. Herein, xe2x80x9cthe arrangement, as a two-dimensional view, approximately in parallelxe2x80x9d means an arrangement substantially in parallel when the unit is viewed from the top. For example, even if the parts-feeding path and the parts-collecting path are not parallel with each other in a strict sense, as long as both of the paths are closely arranged with each other so that it is possible to deliver parts throughout the whole length of a range where both are mutually juxtaposed, such a construction is included in the present invention.
In the present invention, it is preferable that said parts-collecting path is arranged, throughout its whole length, downward with respect to said parts-feeding path. According to this invention, since the parts-collecting path is, throughout its whole length, arranged downward with respect, to the parts-feeding path, the distance between the first linear-transferring means and the second linear-transferring means can be sufficiently secured while providing a construction so that parts can be transferred between both of the paths. Therefore, problems such that parts and/or dust intruding in the gap between both in different vibrating modes, causing a motion failure can be prevented. In addition, since the parts-collecting path is arranged downward, it becomes easy to provide a construction so that a drop distance of parts at a delivery from the second linear-transferring means to the parts-receiving portion of the parts-lifting means can be reduced. Therefore, the impact that parts receive can be suppressed and it also becomes possible to prevent damage to the parts.
Then, a vibratory parts-feeding unit of a second invention is characterized in that the parts-collecting path is, throughout its whole length, arranged downward with respect to the parts-feeding path. According to this invention, since the parts-collecting path is, throughout its whole length, arranged downward with respect to the parts-feeding path, it becomes possible to arbitrarily set the range for delivering parts between the parts-feeding path and parts-collecting path, therefore, it becomes possible to freely design the length of the parts-screening portion on the parts-feeding path. In addition, the distance between the first linear-transferring means and the second linear-transferring means can be sufficiently secured while providing a construction so that parts can be transferred between both of the paths, therefore, problems such that parts and/or dust intruding in the gap between both in different vibrating modes, causing a motion failure can be prevented. In addition, since the parts-collecting path is arranged downward, it becomes easy to provide a construction so that a drop distance of parts at a delivery from the second linear-transferring means to the parts-receiving portion of the parts-lifting means can be reduced, therefore, the impact that parts receive can be suppressed and it also becomes possible to prevent damage to the parts.
In the present invention, it is preferable that a first vibrating body on which said parts-feeding path is constructed and a second vibrating body on which said parts-collecting path is constructed are provided, and said first vibrating body is overhanging said second vibrating body. Thereby, parts can be smoothly transferred and mounted from the parts-feeding path via the parts rejecting portion and the like onto the parts-collecting path, and also it becomes possible to secure a great gap between both vibrating bodies, where both vibrating bodies are opposed horizontally below the overhanging portion. Therefore, maintainability is improved, and also a motion failure caused by, for example, contact between the first vibrating body and second vibrating body via dust, etc., can be prevented.
In the present invention, it is preferable that said parts-collecting path is arranged approximately in parallel with respect to said parts-feeding path when viewed in the up-and-down direction. According to this invention, since the parts-collecting path is arranged approximately in parallel with respect to the parts-feeding path when viewed in the up-and-down direction, delivery of parts from the parts-feeding path to the parts-collecting path becomes possible throughout nearly the whole length of a portion where the parts-feeding path and the parts-collecting path are juxtaposed. Therefore, a long parts-screening portion can be secured on the parts-feeding path and, also, it becomes possible to shorten the length of the unit in the parts feeding direction, whereby the unit can be downsized.
In the present invention, it is preferable that said parts-feeding path and said parts-collecting path are constructed to be approximately horizontal. According to this invention, the parts-feeding path and the parts-collecting path are both constructed to be almost horizontal, whereby it becomes possible to transfer parts by the first linear-transferring means and the second linear-transferring means without difficulty. Therefore, the transferring rate of parts can be heightened, thus it becomes possible to improve the feeding rate of parts.
In the present invention, it is preferable that said parts-lifting means is provided with a spiral parts-lifting path on the outer circumference thereof and transfers parts upward along said parts-lifting path. According to this invention, since the spiral parts-lifting path is provided on the outer circumference, the parts-lifting means can be constructed in a compact size, and also a construction can be provided so that the downstream end of the parts-collecting path directly faces onto the parts-receiving portion located at a lower portion of the parts-lifting means. Therefore, the drop distance of parts at a delivery of the parts can be reduced, whereby damage to the parts can be prevented. For example, in a case where a conventional bowl-shaped vibrating tray is used as parts-lifting means, it is necessary to provide a construction so that the parts-collecting path exceeds the upper edge of the vibrating tray, therefore, parts are easily damaged as they drop from the parts-collecting path arranged above the vibrating tray onto the inner bottom portion of the vibrating tray. In this case, it is desirable that the above parts-lifting means is a vibratory conveyer, which transfers parts along the parts-lifting path by vibration.
In the present invention, it is preferable that, on the first linear-transferring means, parts-discharging portions for discharging parts from said parts-feeding path are provided on both sides of said parts-feeding path, respectively. According to this invention, since the parts-discharging portions are provided on both sides of the parts-feeding path of the first linear-transferring means, screening of parts can be further easily performed. For example, on the parts-feeding path, a part, which overlaps with one side of a certain part, can be rejected to the parts-discharging portion on the said one side, and a part, which overlaps with the other side, can be rejected to the parts-discharging portion on the said other side. Therefore, the screening rate and screening accuracy can be heightened.
In this case, it is desirable that a parts-discharging path which passes below said parts-feeding path and faces onto said parts-collecting path of said second linear-transferring means is connected to said parts-discharging portion for discharging parts onto the side opposite to said second linear-transferring means out of said parts-discharging portions. Herein, in a prior circulating parts-feeding unit, a great difference in elevation (vertical interval) cannot be created between the parts-feeding path of the first linear-transferring means and the parts-collecting path of the second linear-transferring means, which are arranged in a mutually crossing fashion. If a great difference in elevation is created in the prior unit, the angle of inclination of the parts-collecting path of the second linear-transferring means becomes great, making collection of parts difficult and the first and second linear-transferring means long, and as a result, the overall length of the unit must be extended. Therefore, in the prior unit it is structurally impossible to guide parts from the parts-discharging portion for discharging parts onto the side opposite to the second linear-transferring means toward the parts-collecting path of the second linear-transferring means even if the parts-discharging portions are provided on both sides of the parts-feeding path.
Compared hereto, in the present invention, since it is unnecessary to arrange the parts-feeding path and the parts-collecting path in a crossing fashion, it becomes possible to secure a great difference in elevation between both, whereby an advantage is provided such that it becomes possible to guide parts discharged onto the side opposite of the second linear-transferring means to the parts-collecting path of the second linear-transferring means by passing these parts below the parts-feeding path.
In the above respective inventions, it is preferable that installation is carried out so that the parts-collecting path of the second linear-transferring means becomes approximately horizontal or declivitous. Since alignment of parts is unnecessary on the parts-collecting path, by carrying out installation so that the parts-collecting path becomes approximately horizontal or declivitous, parts can be speedily collected.
In addition, the parts-lifting means is not limited to a vibratory conveyer. A mechanical conveyer, a conveyer using fluid pressure (for example, a conveyer which conveys parts by using fluid pressure inside a tube) or the like can be used. Furthermore, the introducing position of parts may be on the parts-collecting path of the second linear-transferring means or on the parts-lifting path of the parts-lifting means.
In addition, in the above respective means, a first vibrating body on which the parts-feeding path is constructed and a second vibrating body on which the parts-collecting path is constructed are provided, and a first vibrating source is arranged below the first vibrating body and a second vibrating source is arranged below the second vibrating body in some cases. Herein, as each vibrating source, a vibrating source containing an electromagnetic driver (for example, a solenoid) can be used, however, in the respect where no influence due to electromagnetic fields is exerted on parts and, in addition, downsizing is possible, a vibrating source containing a piezoelectric driver (a member which produces vibration by a behavior of piezoelectric material) is preferable. In either case, a construction wherein each driving body and an elastic member (a flat spring, a coil spring or the like) are contained can be provided.
In this case, it is preferable to provide a difference in elevation between the installation height of the first vibrating body and the first vibrating source and the installation height of the second vibrating body and the second vibrating source in a manner roughly corresponding to the difference in elevation between the parts-feeding path and the parts-collecting path. The vibrating mode of each vibrating body is produced according to the driving mode of each vibrating source and the distance from each vibrating source to each vibrating body. Therefore, by reducing the difference in the above distance, it becomes possible to easily match the vibrating modes of the first vibrating body and the second vibrating body, thus a desirable correspondence between the parts feeding rate on the parts-feeding path and the parts collecting rate on the parts-collecting path can be obtained.